dProxy - document proxy

dProxy is a proxy to access interface{} (document) by simple query. It is intented to be used with json.Unmarshal() or json.NewDecorder().

See codes for overview.

import (
  "encoding/json"

  "github.com/koron/go-dproxy"
)

var v interface{}
json.Unmarshal([]byte(`{
  "cities": [ "tokyo", 100, "osaka", 200, "hakata", 300 ],
  "data": {
    "custom": [ "male", 23, "female", 24 ]
  }
}`), &v)

// s == "tokyo", got a string.
s, _ := dproxy.New(v).M("cities").A(0).String()

// err != nil, type not matched.
_, err := dproxy.New(v).M("cities").A(0).Float64()

// n == 200, got a float64
n, _ := dproxy.New(v).M("cities").A(3).Float64()

// can be chained.
dproxy.New(v).M("data").M("custom").A(0).String()

// err.Error() == "not found: data.kustom", wrong query can be verified.
_, err = dproxy.New(v).M("data").M("kustom").String()

Getting started

Proxy

1. Wrap a value (interface{}) with dproxy.New() get dproxy.Proxy.

   p := dproxy.New(v) // v should be a value of interface{}

2. Query as a map (map[string]interface{})by M(), returns dproxy.Proxy.

   p.M("cities")

3. Query as an array ([]interface{}) with A(), returns dproxy.Proxy.

   p.A(3)

4. Therefore, can be chained queries.

   p.M("cities").A(3)

5. Get a value finally.

   n, _ := p.M("cities").A(3).Int64()

6. You'll get an error when getting a value, if there were some mistakes.

   // OOPS! "kustom" is typo, must be "custom"
   _, err := p.M("data").M("kustom").A(3).Int64()
   
   // "not found: data.kustom"
   fmt.Println(err)

7. If you tried to get a value as different type, get an error.

   // OOPS! "cities[3]" (=200) should be float64 or int64.
   _, err := p.M("cities").A(3).String()
   
   // "not matched types: expected=string actual=float64: cities[3]"
   fmt.Println(err)

8. You can verify queries easily.

Drain

Getting value and error from Proxy/ProxySet multiple times, is very awful. It must check error when every getting values.

p := dproxy.New(v)
v1, err := p.M("cities").A(3).Int64()
if err != nil {
    return err
}
v2, err := p.M("data").M("kustom").A(3).Int64()
if err != nil {
    return err
}
v3, err := p.M("cities").A(3).String()
if err != nil {
    return err
}

It can be rewrite as simple like below with dproxy.Drain

var d Drain
p := dproxy.New(v)
v1 := d.Int64(p.M("cities").A(3))
v2 := d.Int64(p.M("data").M("kustom").A(3))
v3 := d.String(p.M("cities").A(3))
if err := d.CombineErrors(); err != nil {
    return err
}

JSON Pointer

JSON Pointer can be used to query interface{}

v1, err := dproxy.New(v).P("/cities/0").Int64()

or

v1, err := dproxy.Pointer(v, "/cities/0").Int64()

See RFC6901 for details of JSON Pointer.

LICENSE

MIT license. See LICENSE.